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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetics and Management of Sclerotinia and Related Pathogens of Grain Legumes

Location: Grain Legume Genetics Physiology Research

Project Number: 2090-21000-029-08
Project Type: Specific Cooperative Agreement

Start Date: Sep 01, 2011
End Date: Aug 31, 2016

Objective:
The primary objective of the project is to investigate molecular genetics and pathogenic mechanisms of Sclerotinia spp. and related pathogens of pea, chickpea and lentil. The second objective is to investigate and develop management practices for diseases of pea, chickpea and lentil.

Approach:
1. Pathogen strains will be collected from infected cool season grain legume plants from various geographic regions. Standard mycological techniques will be used to obtain pure cultures. Isolates will be maintained in cellulose filter paper and in 15% glycerol at -75 C. Additional isolates will be obtained from cooperators from other locations under appropriate USDA, Animal and Plant Health Inspection Service (APHIS) permits. 2. Total genomic DNA will be isolated from each isolate using standard DNA isolation procedure and quantified using spectrophotometric method to study population structure of the grain legume pathogens. Various DNA markers including microsatellite markers of the isolates will be determined using PCR, and haplotypes (multi locus genotype or combination of microsatellite alleles) will be determined for each isolate and used in analysis using clustering and Bayesian methods. 3. To investigate pathogenic mechanisms of the grain legume pathogens, genomic segments related to or responsible for pathogenesis will be identified through generation of non-pathogenic mutants of the pathogens. Random mutagenesis will be used to generate tagged mutations and mutants will be screened for virulence. Mutants with altered virulence will be further characterized in terms of genetic mutations and function of the mutated genes, and other genomic methods like transcriptomics. Targeted mutagenesis (gene knockout) will be used to investigate and confirm functions of specific genes. 4. Some secondary metabolites like toxins of fungal pathogens play important roles in causing diseases. To study secondary metabolites of the fungal pathogens, pathogen cultures will be grown in appropriate culture media. Secreted metabolites from the cultures will be isolated and purified using appropriate solvents and concentrated in rotary evaporator, detected and quantified using high performance liquid chromatography. Unknown compounds will be identified using nuclear magnetic resonance spectroscopy and mass spectrometer. Biological activities of the secondary metabolites will be tested using appropriate bioassays. 5. To identify resistance sources to diseases in grain legumes, germplasm lines and cultivars of pea, chickpea and lentil will be planted in the greenhouse. At appropriate growth stages, the test plants will be inoculated with the target pathogens and incubated for disease development at environmental conditions conducive to disease development. Disease severity of the plant genotypes will be scored with appropriate rating scale and resistance will be rated and evaluated in repeated experiments.

Last Modified: 12/21/2014
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